UNIVERSITY OF VIRGINIA PUBLICATIONS 



BULLETIN 



OF THE 



PHILOSOPHICAL SOCIETY 



Scientific Series, Vol. I, No. 20, pp. i 3 7-442, July, 1914 



Examples of Intercision Type of Stream Piracy 
in Western Virg'inia 



BY 



THOMAS L. WATSON, JUSTUS H. CLINE, AND 
THO'kAS K. HARNSBERGER 



V 



UNIVERSITY OF VIRGINIA 
CbarlottesTille, Viripmift, U. S. A. 



'•.Ts;,) 



UNIVERSITY OF VIRGINIA PUBLICATIONS 

The Proceedings and Transactions of the Philosophical Society of the University 
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cations should be addressed to Dr. Thomas L. Watson, University, Virginia. 

Thus far have been published the following papers. 

SCIENTIFIC SECTION 

1. Intermediate (Quartz Monzonitic) Character of the Central and Southern Appa- 

lachian Granites, with a Comparative Study of the Granites of New England 
and the Western United States. By Thomas L. Watson. Vol. I, pp. 1-40. 
Price $0.75. 

2. On Chemical Interaction of Substances in the Solid State. By J. W. Mallet, 

Vol. I, pp. 41-44. Price S0.25. 

3. On the Maximum and Minimum Values of a Linear Function of the Radial Co- 

ordinates of a Point with respect to a Simplicissimum in Space of n Dimensions. 
By W. H. Echols. Vol. I, pp. 45-84. Price $0.75., 

4. New Positions of the Stars in the Huyghenian Region of the Great Nebula in 

Orion. By R. E. Wilson. Vol. I, pp. 85-126. Price S3.75. 

5. On the Flow of Water in Pipes, Conduits and Open Channels and the Losses of 

Energy Due to its Motion. By W. H. Echols. Vol. I, pp. 127-186. Price 
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6. An Investigation of the Value of an Infinite Series on the Boundary of the Region 

of Convergence. By W. H. Echols. Vol. I, pp. 187-199. Price $0.25. 

7. A Contribution to the Geology and Mineralogy of Graves Mountain, Georgia. 

By Thomas L. and J. Wilbur Watson. Vol. I, No. 7. Price $0.25. 
So An Unusual Occurrence of the Mineral Evansite. By John Sharshall Grasty. 

Vol. I, No. 8. Price $0.25. 
9. On a Certain Quadratic Form with its Geometric and Kinematic Interpretations. 

By W. H. Echols, Vol. I, No. 9. Price $0.25. 

10. The Flow of Water in Artificial Channels: Clean Pipes. With three Plates. By 

W.H.Echols. Vol.1, No. 10. Price $0.50. 

11. Zirconiferous Sandstone near Ashland, Virginia, with a Summary of the Prop- 

erties, Occurrence, and Uses of Zircon in General. By Thomas L. Watson and 
Frank L. Hess. Vol. I, No. 11. Price $0.50. 

12. Studies In Human Heredity. By H. E. Jordan. Vol. I, No. 12. Price $0.40. 

13. The Evolutionary Construction of the Imaginary Power of a Number and its 

Expression as the Exponential Function. By W. H. Echols. Vol. I, No. 13. 
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14. Magmatic Names Proposed in the Quantitative System of Classification for some 

New Rock Types in Virginia. By Thomas L. Watson and Stephen Taber. 
Vol. I, No. 14. Price $0.25. 

Continued on page 3 of cover 






I (^^4^ 



UNIVERSITY OF VIRGINIA PUBLICATIONS 

BULLETIN OF THE PHILOSOPHICAL SOCIETY 

SCIENTIFIC SECTION 

Vol. I, No. 20, pp. 437-442 July, 1914 



EXAMPLES OF INTERCISION TYPE OF STREAM PIRACY IJs^ 

WESTERN VIRGINIA 

By 

THOMAS L. WATSON, JUSTUS H. CLINE, 
AND THOMAS K. HARNSBERGER. 

During the progress of systematic field work by the "Virginia Geological 
Survey in western Virginia, a type of stream capture due to the removal 
of divides by lateral planation was studied by the writers. Three cases 
have been selected which illustrate different stages of the process and 
while they involve no new physiographic principle, they illustrate an 
interesting type of drainage change. 

The removal of divides by lateral planation is the last work accom- 
plished by streams in the base leveling process; consequently captures 
due to lateral shifting of the position of streams under conditions of old 
age must be common. In the lower Mississippi Valley, for instance, 
many such captures have occurred or are about to occur. In such regions 
where streams have passed the stage of maturity the accompanying physio- 
graphic results are apt to be slight. In regions of more youthful or mature 
drainage, stream captures affected by lateral planation are of less frequency, 
but are likely to be attended by more or less prominent physiographic 
consequences. In case III described below a water gap has been devel- 
oped in this way, and in case II a natural bridge may result. 

When captures due to lateral planation occur under conditions other 
than those of old age the disposition to such capture^ will usually have 
been inherited from a previous cycle of erosion. In each case described 
below the stream occupies an entrenched meandering valley characteristic 
of a rejuvenated region. These meanders existed at the beginning of the 
present cycle, and therefore a tendency toward lateral planation was 
probably manifested at a relatively early stage. In a rejuvenated region 

437 



438 UNIVERSITY OF VIRGINIA PUBLICATIONS 

of meandering streams some lateral planation may occur with the down 
cutting at an early stage in the cycle. Thus North River near Bridge- 
water, Rockingham County, has considerably increased the distance 
between it and Round Hill on one side since the inauguration of the 
present cycle, and on the other side it has invaded the hill itself — the 
difference in the two cases being due to the position of the hill with refer- 
ence to the meanders of the stream. 

Three fairly typical examples illustrating different stages in the process 
of stream capture by lateral planation are described below. By consult- 
ing the accompanying topographic maps (figs. 1, 2, and 4), it will be 
oljserved that each of these cases is found in a rejuvenated region. The 
stage of development represented in the present cycle in these cases appar- 
ently ranges from late youth to maturity. The first case described is in 
Dickenson County in the Alleghany Plateau region of southwest Virginia. 
The capture has not yet taken place, but geologically speaking it is immi- 
nent. The second case illustrates the same type of capture in process of 
taking place, and the third shows that it has already occurred. The 
last two cases are in Rockingham County in the Shenandoah Valley. 

The type of stream piracy illustrated by these three cases is designated 
by the writers the intercision type. The term intercision was used by 
Goldthwait* in describing a peculiar change in drainage near Kenosha, 
Wisconsin, where the narrow divide between Lake Michigan and the 
lower part of the meandering valley of Pike River has been removed in 
places by the combined work of the lake and stream, and the lower part 
of the stream severed from its upper course. 

Case I. The accompanying topographic map (fig. 1) of a small area 
in Dickenson County, southwest Virginia, shows the existing topographic 
conditions in this case. The rocks are sandstones and shales and are 
very gently folded. The region is thoroughly dissected but the streams, 
which are of the rejuvenated type, are actively engaged in eroding their 
valleys deeper. The streams have inherited meandering courses from a 
previous cycle. 

It will be observed by consulting the map (fig. 1) that a meander in 
the valley of Pound River at a point about 3 miles from its junction with 
Russell Fork brings it very close to that of one of its tributaries. Cane 
Branch. The minimum distance between the two streams is about 300 
feet, and Pound River is flowing at a level more than 100 feet below its 
tributary (Cane Branch). The divide between the two streams is being 

* Goldthwait, J. W., Intercision, a peculiar kind of modification of drainage. 
School Science and Mathematics, 1908, vol. 8, no. 2, pp. 129-139. 



^ 



INTERCISION TYPE OF STREAM PIRACY 



439 



slowly removed chiefly by Pound River which is not only deepening its 
valley at this point but is also advancing laterally in the direction of Cane 
Branch by undercutting the divide. Ultimately a breach will be made 
in the divide at this point with the result that the junction of the two 
streams will be moved one and a quarter miles up stream and the 
lower part of the valley of Cane Branch abandoned. 




Fig. 1. Topographic Map of a Part of the Northwest Corner of Dick- 
enson County, Virginia, Showing Relations of Pound River to its Tribu- 
tary, Cane Creek. 

Scale 1.318 inches = 1 mile. 

Contour interval 50 feet. 

Case II. The second example (see map, fig. 2) is at the vil'age of 
Mt. Crawford, Rockingham County, 18 miles northeast of Staunton. 
The rocks of the region are ehiefly limestones which have been highly 
folded and faulted. The two streams involved in this case are North 
Fork of the Shenandoah River and one of its tributaries, Cook's Creek. 



440 



UNIVERSITY OF VIRGINIA PUBLICATIONS 



Both streams are flowing in entrenched meandering valleys and both have 
developed flood plains in places. The physiography of the immediate 
section is shown on the accompanying map (fig. 2). The chief interest 
in this case is that the capture is in actual process of taking place. 

The distance between the two streams at the nearest point is about 
150 feet. The divide is occupied by the valley pike which extends from 




Fig. 2. Topographic Map of Mt. Crawford and Vicinity, Rockingham 
County, Virginia, Showing Relations of North River and its Tributary, 
Cook's Creek. 

Scale 2.667 inches = 1 mile. 

Contour intervals 10 and 20 feet. 



Winchester to Staunton. It is composed of more or less massive be^s 
of limestone which dip about 10 degrees southeast, and are jointed but 
not brecciated. Cook's Creek is flowing at an elevation of 14 feet above 
the main stream, North River. A part of the water from Cook's Creek 



INTERCISION TYPE OF STREAM PIRACY 



441 



has found its way through the divide along joint and bedding planes, so 
that the two streams are now connected by a subterranean passage. This 
channel has been enlarged by solution, so that now a sufficient volume of 
water passes through it from Cook's Creek to North River to cause alarm 
on the part of the owners of a mill located a short distance below, who 
depend on the water of Cook's Creek for power. Several attempts have 
been made to stop the underground passage but without success. The 
amount of water which flows through the underground channel varies 
with the stage of water in the two streams, but especially with that in 
Cook's Creek. 

The point where the water emerges on the face of the bluff on the 
North River side of the divide is about 2 or 3 feet above low water in 
North River, but at high water the opening is frequently submerged. 




10 25 



50 



100 FEET. 



Fig. 3. Cross Section of Divide Between North River and Cook's Creek. 



The source of the water flowing from the underground channel is deter- 
mined readily, since the water of Cook's Creek is usually stained very 
dark by the refuse from a tannery at Harrisonburg. A cross section of 
the divide between North River and Cook's Creek is shown in figure 3. 

Case III. Reference to the map (fig. 4) of Bridgewater and vicinity 
will show that North River flows in a meandering course through a ridge 
about 1 mile northwest of the town. This ridge is typical of numerous 
low linear cherty ridges which characterize the Great Valley in western 
Virginia. Round Hill is one of the common conical-shaped monadnocks 
which occur at intervals in these cherty ridges throughout the Valley 
province. The rocks composing this ridge are for the most part massive- 
bedded cherty limestones, the most resistant members of the Shenandoah 
group. The ridge is monocUnal in structure, the beds dipping toward the 
southeast. 



442 UNIVERSITY OF VIRGINIA PUBLICATIONS 

Dry River, a tributary of North River, likewise crosses this ridge 
about three-fourths of a mile northeast of the junction of the two streams. 
The point in the ridge where it is crossed by Dry River is less cherty than 
in the vicinity of North River and therefore Dry River, although the 
smaller Qf the streams, occupies the larger of the two valleys. 

The peculiar feature in the case of Dry River after passing the cherty 
ridge is that it has abandoned the lower portion of its valley which was 
developed in less resistant rocks, flows back again into the cherty ridge 
area and joins North River more than half a mile above the point where 
the latter stream leaves the ridge. 

The almost level plain south of the Chesapeake and Western Railway 
is the abandoned southern extension of Dry River valley. This plain 
is composed of alluvial material, such as sand, gravel, loam, clay, and in 
places numerous large river boulders. There are also traces of stream 
channels in the form of linear and meandering depressions. The boundary 
between this plain and the present flood plain of North River immedi- 
ately above and below Bridgewater is marked by a distinct terrace with 
an average difference in elevation of 10 to 20 feet between the two plains. 
This terrace can be traced all the way from the point where North River 
emerges from the cherty ridge to the vicinity of Berlinton, a distance of 
IJ miles. 

The explanation of this interesting physiography is that Dry River 
formerly entered North River near Berlinton about If miles below their 
present junction. For some distance above their old junction the two 
streams had a common flood plain, but at the point of their present junc- 
tion their valleys were separated by a narrow cherty ridge. Finally . a 
breach was made in this cherty ridge by the two streams which had swung 
against it at opposite points. Since North River was the larger stream 
and therefore flowing at a lower level it captured the waters of Dry River. 
The streams do not meet at grade but there is a fall of 2 or 3 feet in Dry 
River a few yards above their junction. 

The results of the capture were the abandoning of the valley of Dry 
River between the point of capture and the old junction, and the rejuve- 
nation of that part of North River between these points by increase in 
volume of water. The result of this rejuvenation has been the marked 
lowering of the flood plain of North River between the point where it 
leaves the cherty ridge and Berlinton. The present flood plain of North 
River is 10 to 20 feet below the level of the common flood plain of the 
two streams before the capture took place. 




Fig. 4. To 




Fig. 4. Topographic Map op Bridqbwatbr and Vicinity, Rockingham County, Virginia. 
Scale 2.667 inches = 1 mile. 
Contour intervals 10 and 20 feet. 



L 



mm 



■■HHH 



mmm 



- . * - -I. - • I. 



15. On the Root of a Monogenic Function Inside a Closed Contour along which the 

Modulus is Constant. By William H. Echols. Vol. I, No. 15. Price. S0.25. 

16. Normal Faulting in the Cambrian of Northern Piedmont, Virginia, By Thomas 

L. Watson and Justus H. Cline. Vol. I, No. 16. Price $0.25. 

17. Drainage Changes in the Shenandoah Vall6y Region of Virginia. By Thomas L. 

Watson and Justus H. Cline. Vol. I, No. 17. Price $0.50. 

18. The Association of Vanadium with Petroleum and Asphalt. By R. M: Bird and 

W. S. Calcott. Price $0.25. 

19. Locoweed Disease of Sheep. By Harry T. Marshall. Vol. I, No. 10. Price 

$0.50. 

20. Examples of Intercision Type of Stream Piracy in Western Virginia. Vol. I, 

No. 20. By Thomas L. Watson, Justus H. Cline, and Thomas K. Harns- 
berger. Price $0.25. 

HUMANISTIC SECTION 

1. The Sacred Tripudium. By Thomas Fitz-Hugh. Vol. I, pp. 1-50. Price $0.75. 

2. Keller's der Griine Heinrich: Anna and Judith and their Predecessors in Rous> 

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